"The KDE community today announces the start of the Calligra Suite project, a continuation of the KOffice project. The new name reflects the wider value of the KOffice technology platform beyond just desktop office applications. With a new name for the Suite and new names for the productivity applications, the Calligra community welcomes a new stage in the development of free productivity and creativity applications for desktop and mobile devices."

Word is a trademark, not Words. Trademark are only on the exact same spelling.

This is not true at all. If one can demonstrate that a name is similar enough to be confusing within the same industry, then there's a good case for trademark infringement.

It is why Adida or Addidas are legal brand even if it look like Adidas (this example is getting old).

Never heard that example personally - assuming these are shoe brands, and being distributed in a country where the Adidas brand is trademarked, they have an extremely compelling case there. However, if they don't pursue it legally, then they forfeit the ability to enforce their trademark against these names after a period of time.